A hot water supply system is a system configured to heat cold water so that the water has a predetermined temperature in a short time and supply the hot water so that a user conveniently uses the hot water.
Such a hot water supply system burns oil or gas as a fuel using a burner, heats water using combustion heat generated during a combustion process, and provides the heated water to a user as necessary.
While the user opens a hot water valve to use hot water, and an operation for hot water is started, and hot water is heated to an optimal temperature, since cold water is discharged and thrown away through a hot water discharging port, waste of water energy occurs, the user has to wait until the hot water having the optimal temperature is supplied, and thus there is a problem in that hot water use is inconvenient.
To solve such a problem, “Method for controlling hot water pre-heating of hot water heater according to hot water using pattern of user” is disclosed in Korean Patent Publication No. 10-2013-0126299.
According to the related art of the method of preheating water, it is determined that water needs to be preheated according to a hot water using pattern of a user, and the water is preheated prior to being used by the user.
However, when the user preheats water prior to using the hot water, energy may be wasted.
FIG. 1 is a view illustrating a conventional hot water supply system which is a system configured to preheat water while circulating the water in a case in which a water-preheating signal of a user is detected.
The hot water supply system of FIG. 1 includes a water-preheating signal generating unit 50 configured to generate a water-preheating signal by detecting a case in which a user desires to preheat water using a sensor or when a user pushes a button, and when the water-preheating signal is input in a control unit, the control unit operates a circulation pump 40 to sequentially circulate water supplied from a hot water supply apparatus 20 through a hot water supply pipe 12, the circulation pump 40, a cold water supply pipe 13, a cold water inflow pipe 11, and a hot water supply apparatus 20 to preheat water. After such a preheating process is performed, when the user opens a hot water valve 31, the hot water having a temperature desired by the user is supplied.
A reference numeral “10,” “30,” and “32” respectively denote a cold water inflow pipe through which cold water is introduced, a tap, and a cold water valve.
However, according to such a conventional hot water supply system, the circulation pump 40 is provided on a pipe connected to the hot water supply pipe 12 and the cold water supply pipe 13, and hot water and cold water may be mixed through the connected pipe. Accordingly, when a user opens the cold water valve 32 to use cold water while hot water circulates for preheating, there is a problem in that the hot water in the hot water supply pipe 12 is discharged through the circulation pump 40 and the cold water valve 32. Conversely, when the user opens the hot water valve 31 to use hot water in a state in which an operation of the circulation pump 40 is stopped, there is a problem in that cold water of the cold water supply pipe 13 is discharged through the circulation pump 40 and the hot water valve 32.